leukotriene-b4 and Pneumonia--Bacterial

To determine the effects of oral administration of tilmicosin in piglets experimentally infected with Actinobacillus pleuropneumoniae.. Forty 3-week-old specific-pathogen free piglets.. Piglets were assigned to 1 of 4 groups as follows: 1) uninfected sham-treated control piglets; 2) infected untreated piglets that were intratracheally inoculated with 10(7) CFUs of A pleuropneumoniae; 3) infected treated piglets that were intratracheally inoculated with A pleuropneumoniae and received tilmicosin in feed (400 ppm [microg/g]) for 7 days prior to inoculation; or 4) infected treated piglets that were intratracheally inoculated with A pleuropneumoniae and received chlortetracycline (CTC) in feed (1100 ppm [microg/gl) for 7 days prior to inoculation. Bronchoalveolar lavage (BAL) fluid and lung tissue specimens of piglets for each group were evaluated at 3 or 24 hours after inoculation. For each time point, 4 to 6 piglets/group were studied.. Feeding of CTC and tilmicosin decreased bacterial load in lungs of infected piglets. Tilmicosin delivered in feed, but not CTC, enhanced apoptosis in porcine BAL fluid leukocytes. This was associated with a decrease in LTB4 concentrations in BAL fluid of tilmicosin-treated piglets, compared with untreated and CTC-treated piglets, and also with a significant decrease in the number of pulmonary lesions. Tilmicosin inhibited infection-induced increases in rectal temperatures, as measured in untreated and CTC-treated piglets. Pulmonary neutrophil infiltration and prostaglandin E2 concentrations in the BAL fluid were not significantly different among groups at any time.. Oral administration of tilmicosin to infected piglets induces apoptosis in BAL fluid leukocytes and decreases BAL fluid LTB4 concentrations and inflammatory lung lesions.

Topics: Actinobacillus Infections; Actinobacillus pleuropneumoniae; Animal Feed; Animals; Anti-Inflammatory Agents, Non-Steroidal; Apoptosis; Dinoprostone; Leukocytes; Leukotriene B4; Macrolides; Peroxidase; Phagocytosis; Pneumonia, Bacterial; Swine; Swine Diseases; Tylosin

To investigate the anti-inflammatory and immunomodulatory properties of tulathromycin in vitro and in experimental models of Actinobacillus pleuropneumoniae-induced pleuropneumonia and zymosan-induced pulmonary inflammation in pigs.. Blood samples from six 8- to 30-week-old healthy male pigs for the in vitro experiment and sixty-five 3-week-old specific pathogen-free pigs.. Neutrophils and monocyte-derived macrophages were isolated from blood samples. Isolated cells were exposed to tulathromycin (0.02 to 2.0 mg/mL) for various durations and assessed for markers of apoptosis and efferocytosis. For in vivo experiments, pigs were inoculated intratracheally with A pleuropneumoniae, zymosan, or PBS solution (control group) with or without tulathromycin pretreatment (2.5 mg/kg, IM). Bronchoalveolar lavage fluid was collected 3 and 24 hours after inoculation and analyzed for proinflammatory mediators, leukocyte apoptosis, and efferocytosis.. In vitro, tulathromycin induced time- and concentration-dependent apoptosis in neutrophils, which enhanced their subsequent clearance by macrophages. In the lungs of both A pleuropneumoniae- and zymosan-challenged pigs, tulathromycin promoted leukocyte apoptosis and efferocytosis and inhibited proinflammatory leukotriene B4 production, with a concurrent reduction in leukocyte necrosis relative to that of control pigs. Tulathromycin also attenuated the degree of lung damage and lesion progression in A pleuropneumoniae-inoculated pigs.. Tulathromycin had immunomodulatory effects in leukocytes in vitro and anti-inflammatory effects in pigs in experimental models of A pleuropneumoniae infection and nonmicrobial-induced pulmonary inflammation. These data suggested that in addition to its antimicrobial properties, tulathromycin may dampen severe proinflammatory responses and drive resolution of inflammation in pigs with microbial pulmonary infections.

Topics: Actinobacillus Infections; Actinobacillus pleuropneumoniae; Animals; Anti-Inflammatory Agents; Apoptosis; Disaccharides; Heterocyclic Compounds; Leukocytes; Leukotriene B4; Male; Phagocytosis; Pneumonia, Bacterial; Specific Pathogen-Free Organisms; Swine; Swine Diseases; Zymosan

Bioactive matrix fragments (matrikines) have been identified in a myriad of disorders, but their impact on the evolution of airway inflammation has not been demonstrated. We recently described a pathway where the matrikine and neutrophil chemoattractant proline-glycine-proline (PGP) could be degraded by the enzyme leukotriene A4 hydrolase (LTA4H). LTA4H classically functions in the generation of pro-inflammatory leukotriene B4, thus LTA4H exhibits opposing pro- and anti-inflammatory activities. The physiological significance of this secondary anti-inflammatory activity remains unknown. Here we show, using readily resolving pulmonary inflammation models, that loss of this secondary activity leads to more pronounced and sustained inflammation and illness owing to PGP accumulation. PGP elicits an exacerbated neutrophilic inflammation and protease imbalance that further degrades the extracellular matrix, generating fragments that perpetuate inflammation. This highlights a critical role for the secondary anti-inflammatory activity of LTA4H and thus has consequences for the generation of global LTA4H inhibitors currently being developed.

Topics: Animals; Epoxide Hydrolases; Extracellular Matrix; Flow Cytometry; Haemophilus Infections; Haemophilus influenzae type b; Inflammation; Leukocyte Elastase; Leukotriene B4; Lung; Macrophages, Alveolar; Matrix Metalloproteinase 12; Matrix Metalloproteinase 9; Mice; Mice, Knockout; Neutrophils; Oligopeptides; Pneumonia, Bacterial; Pneumonia, Pneumococcal; Proline; Receptors, Leukotriene B4; Streptococcus pneumoniae

In prior studies, we demonstrated that 1) CXCL1/KC is essential for NF-κB and MAPK activation and expression of CXCL2/MIP-2 and CXCL5/LPS-induced CXC chemokine in Klebsiella-infected lungs, and 2) CXCL1 derived from hematopoietic and resident cells contributes to host immunity against Klebsiella. However, the role of CXCL1 in mediating neutrophil leukotriene B(4) (LTB(4)), reactive oxygen species (ROS), and reactive nitrogen species (RNS) production is unclear, as is the contribution of these factors to host immunity. In this study, we investigated 1) the role of CXCL1 in LTB(4), NADPH oxidase, and inducible NO synthase (iNOS) expression in lungs and neutrophils, and 2) whether LTB(4) postinfection reverses innate immune defects in CXCL1(-/-) mice via regulation of NADPH oxidase and iNOS. Our results demonstrate reduced neutrophil influx, attenuated LTB(4) levels, and decreased ROS and iNOS production in the lungs of CXCL1(-/-) mice after Klebsiella pneumoniae infection. Using neutrophil depletion and repletion, we found that neutrophils are the predominant source of pulmonary LTB(4) after infection. To treat immune defects in CXCL1(-/-) mice, we intrapulmonarily administered LTB(4). Postinfection, LTB(4) treatment reversed immune defects in CXCL1(-/-) mice and improved survival, neutrophil recruitment, cytokine/chemokine expression, NF-κB/MAPK activation, and ROS/RNS production. LTB(4) also enhanced myeloperoxidase, H(2)O(2,) RNS production, and bacterial killing in K. pneumoniae-infected CXCL1(-/-) neutrophils. These novel results uncover important roles for CXCL1 in generating ROS and RNS in neutrophils and in regulating host immunity against K. pneumoniae infection. Our findings suggest that LTB(4) could be used to correct defects in neutrophil recruitment and function in individuals lacking or expressing malfunctional CXCL1.

Topics: Animals; Chemokine CXCL1; Chemotaxis, Leukocyte; Drug Evaluation, Preclinical; Female; Klebsiella Infections; Klebsiella pneumoniae; Leukotriene B4; Lung; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; NADPH Oxidases; Neutrophils; Nitric Oxide Synthase Type II; Peroxidase; Pneumonia, Bacterial; Reactive Nitrogen Species; Reactive Oxygen Species

Neutrophil accumulation is a critical event to clear bacteria. Since uncontrolled neutrophil recruitment can cause severe lung damage, understanding neutrophil trafficking mechanisms is important to attenuate neutrophil-mediated damage. While monocyte chemoattractant protein 1 (MCP-1) is known to be a monocyte chemoattractant, its role in pulmonary neutrophil-mediated host defense against Gram-negative bacterial infection is not understood. We hypothesized that MCP-1/chemokine (C-C motif) ligand 2 is important for neutrophil-mediated host defense. Reduced bacterial clearance in the lungs was observed in MCP-1(-/-) mice following Escherichia coli infection. Neutrophil influx, along with cytokines/chemokines, leukotriene B(4) (LTB(4)), and vascular cell adhesion molecule 1 levels in the lungs, was reduced in MCP-1(-/-) mice after infection. E. coli-induced activation of NF-κB and mitogen-activated protein kinases in the lung was also reduced in MCP-1(-/-) mice. Administration of intratracheal recombinant MCP-1 (rMCP-1) to MCP-1(-/-) mice induced pulmonary neutrophil influx and cytokine/chemokine responses in the presence or absence of E. coli infection. Our in vitro migration experiment demonstrates MCP-1-mediated neutrophil chemotaxis. Notably, chemokine receptor 2 is expressed on lung and blood neutrophils, which are increased upon E. coli infection. Furthermore, our findings show that neutrophil depletion impairs E. coli clearance and that exogenous rMCP-1 after infection improves bacterial clearance in the lungs. Overall, these new findings demonstrate that E. coli-induced MCP-1 causes neutrophil recruitment directly via chemotaxis as well as indirectly via modulation of keratinocyte cell-derived chemokine, macrophage inflammatory protein 2, and LTB(4).

Topics: Animals; Bone Marrow Transplantation; Bronchoalveolar Lavage Fluid; Chemokine CCL2; Chemokine CXCL2; Escherichia coli; Escherichia coli Infections; Leukotriene B4; Lung; Mice; Mice, Inbred C57BL; Mice, Knockout; Mitogen-Activated Protein Kinases; Neutrophil Infiltration; NF-kappa B; Pneumonia, Bacterial; Vascular Cell Adhesion Molecule-1

To evaluate the role of Chlamydia pneumoniae respiratory tract infection on pediatric asthma, allergic rhinitis or atopic eczema initiation, children of three age groups (n=1211) were prospectively studied for a C. pneumoniae infection using throat swabs and polymerase chain reaction (PCR) with enzyme immunoassay (EIA) detection. Infected children (study group, SG) were examined monthly until the agent could not be detected, quantifying persistent infection. They were compared with randomly selected, non-infected children without asthma matched for age, gender and origin (control group, CG) regarding lung function and inflammatory parameters as well as initiation of allergic diseases judged by family doctor diagnosis after, in median, 22 months. At the first follow-up examination, SG children revealed a higher leukotriene B4 (median 36 pg/ml vs. 19, p=0.04) and 8-isoprostane (median 15 pg/ml vs. 12, p=0.04) in breath condensate characterizing neutrophil, agent-related inflammation and oxidative stress in the lower airways. Cysteinyl leukotrienes, important in acute allergic inflammation, were without difference. Local, anti C. pneumoniae secretory immunoglobulin A antibodies were higher in children after C. pneumoniae infection (optical density median 0.7 vs. 0.4, p=0.001) confirming PCR-EIA results. At the final examination, there was no difference in pathological lung function tests, parameters of exhaled breath condensate or eosinophilia of the nasal mucosa. Incidence of asthma (0/55 vs. 5/54, p=0.03) and allergic rhinitis [3/53 vs. 10/52, p=0.04, odds ratio and 95% confidence interval-OR 0.25 (0.06;0.98)] as well as prevalence of asthma [1/56 vs. 9/58, p=0.02, OR 0.1 (0.01;0.81)] and allergic rhinitis [6/56 vs. 16/58, p=0.03, OR 0.32 (0.11;0.88)] were lower in the SG children. There was no association in atopic eczema. Three children with persistent infection revealed a slightly higher incidence in allergic rhinitis without significance than those with single C. pneumoniae detection (1/3 vs. 2/50), however, not to the CG. In conclusion a C. pneumoniae upper respiratory tract infection may be regarded as a protective factor for childhood asthma or allergic rhinitis in a population of kindergarten and school-age children.

Topics: Adolescent; Animals; Asthma; Child; Child, Preschool; Chlamydophila Infections; Chlamydophila pneumoniae; Cohort Studies; Dermatitis, Atopic; Dinoprost; Female; Humans; Immunoenzyme Techniques; Immunoglobulin A; Leukotriene B4; Male; Pneumonia, Bacterial; Polymerase Chain Reaction; Respiratory Function Tests; Rhinitis

Human immunodeficiency virus (HIV)-infected patients are at increased risk of contracting bacterial infections, mainly pneumonia. Despite this, little is known about immunopathogenic mechanisms in HIV-related bacterial pneumonia. This paper investigates the presence of the neutrophil chemotactic mediators, interleukin-8 (IL_8) and leukotriene B4 (LTB4), in bronchoalveolar lavage (BAL) fluid from 27 HIV-infected patients with bacterial pneumonia. Significantly elevated levels of IL-8 were found in BAL fluid of patients with bacterial pneumonia [529 pg ml-1 (296-1161 pg ml-1)] compared to matched patients with Pneumocystis carinii pneumonia (PCP) [59 pg ml-1 (42-254 pg ml-1)] and healthy controls [58 pg ml-1 (37-82 pg ml-1)]. Levels of LTB4 were not elevated during bacterial pneumonia when compared to PCP patients and healthy controls. Furthermore, a positive correlation was found between IL-8 levels in BAL fluid and relative BAL neutrophilia (r = 0.60, P = 0.001) in bacterial pneumonia. In conclusion, elevated IL-8 levels in BAL fluid were found in patients suffering from bacterial pneumonia, which may account for the influx of neutrophils to the lung, whereas LTB4 appears not to be an important chemotactic factor in this setting.

Topics: Bronchoalveolar Lavage Fluid; CD4 Lymphocyte Count; Chemotaxis, Leukocyte; Haemophilus Infections; HIV Infections; Humans; Interleukin-8; Leukotriene B4; Neutrophils; Pneumococcal Infections; Pneumonia, Bacterial; Pneumonia, Pneumocystis; Staphylococcal Infections

Leukotrienes (LTs) are potent mediators of inflammation derived from the 5-lipoxygenase pathway of arachidonic acid metabolism. Although they are known to enhance leukocyte recruitment and function, their role in antimicrobial host defense has not been established. To determine the role of endogenous LTs in the host response to pulmonary infection, wild-type mice and mice rendered LT-deficient by targeted disruption of the 5-lipoxygenase gene (knockout mice) were studied following intratracheal challenge with Klebsiella pneumoniae. Wild-type mice demonstrated a marked increase in lung LT levels and neutrophil numbers following bacterial challenge. As compared with wild-type animals, knockout animals manifested a greater degree of lethality as well as bacteremia following challenge. Interestingly, they displayed no defect in neutrophil recruitment to the lung. However, alveolar macrophages from knockout animals exhibited impairments in bacterial phagocytosis and killing, and these defects were overcome by in vitro addition of exogenous LTB4. We conclude that endogenous LTs play a critical role in the defense against bacterial pneumonia in this murine model.

Topics: Animals; Arachidonate 5-Lipoxygenase; Blood Bactericidal Activity; Immunity, Cellular; Klebsiella pneumoniae; Leukotriene B4; Leukotrienes; Macrophages, Alveolar; Mice; Mice, Knockout; Phagocytosis; Pneumonia, Bacterial

Topics: Animals; Bacterial Vaccines; Bronchoalveolar Lavage Fluid; Chemotaxis, Leukocyte; Disease Models, Animal; Humans; Immunity, Mucosal; Immunization; In Vitro Techniques; Intestinal Mucosa; Leukotriene B4; Lung; Male; Neutrophils; Peyer's Patches; Pneumonia, Bacterial; Pseudomonas aeruginosa; Pseudomonas Infections; Rats